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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>


    <script>
        // let 1=;     不能以数字开头
        let n1_$ = "";
        let n = 1;
        let N = true;
        // let var="";  不能使用关键字，保留字
        console.log("NaN是" + NaN)  //非数字类型
        console.log("n1_$是" + typeof (n1_$))
        console.log("n:" + typeof (n))
        console.log("N:" + typeof (N))


        let a = {
            name: "h1",
            type: "block",
            color: "#000",
            fontSize: "60px",
            background: "#fff"
        }
        let b = [
            {
                name: "h1",
                type: "block",
                color: "#000",
                fontSize: "60px",
                background: "#fff"
            },
            {
                name: "h2",
                type: "block",
                color: "#000",
                fontSize: "60px",
                background: "#fff"
            },
            {
                name: "h3",
                type: "block",
                color: "#000",
                fontSize: "60px",
                background: "#fff"
            },
        ]
        // for (let a1 in a) {
        //     console.log(a1 + ":" + a[a1])
        // }
        for (let a2 in b) {
            // console.log(b[a2])
            for (let a3 in b[a2]) {
                console.log(b[a2][a3])
            }
        }
    </script>

</body>

</html>